1. Field of the Invention
The present invention relates to a cutting torch machine having an internal ignition device on a cutting oxygen channel in communication with a mixing stage which generates an ignition gas.
2. Discussion of the Related Art
In conventional cutting torch machines having a cutting oxygen channel, the feeders, i.e., the ducts, are provided on threaded pipe connections for fuel gas and/or heating oxygen, which are connected with a fuel gas and oxygen source. The conventional cutting torch additionally includes a separate adapter nipple leading to a fuel gas-oxygen mixture feeder which leads to the cutting oxygen channel. The fuel gas-oxygen mixture constitutes the ignition gas. At the cutter oxygen channel, an electrical ignition device is provided downstream of the mouth of the fuel gas-oxygen mixture feeder. The fuel gas-oxygen mixture is generated outside of the torch body in a mixing stage designed as an injector. The injector constitutes part of an ignition gas volume control device directly connected to the supply sources for fuel gas and heating oxygen. This should safeguard that an ignition gas volume is fed to the ignition point which is independent from, and uninfluenced by, the adjustment of the fuel gases of the cutting torch (German Offenlegungsschrift No. 35 27 955).
In the branching-off ducts to the injector conducting heating oxygen and fuel gas, the ignition gas volume control device referred to includes a solenoid valve and a pressure control each. In detail, the pressure control is connected via a connecting T piece to a heating oxygen supply source or a fuel gas supply source. Via a threaded adapter, a cutting oxygen duct is further provided on the cutter torch, which is connected via a control and/or regulating device to the cutting oxygen supply source. This means that the supply of the fuel gas-oxygen mixture as the ignition gas is provided simultaneously with the supply of the fuel gas, the heating oxygen and the cutter oxygen to the cutting torch. A special duct is provided for the ignition gas which in practice is designed as a hose. While such hoses are suitable for the supply of ignition gas or fuel gas, the risk of an accident cannot be excluded if the ignition gas, or the fuel gas mixture, respectively, is supplied via the usually long paths. The effort in providing all the gadgets and devices is substantial.
In the conventional system of the separate ignition gas volume control device wherein also the ignition gas is generated and which, to this end, substantially includes the mixer for mixing the ignition fuel gas and the ignition oxygen to obtain the ignition gas mixture, pressure control for the ignition oxygen and the ignition gas, solenoid valves for switching on and off the ignition fuel gas and the ignition oxygen, provided in parallel to the fuel gas and heating oxygen supply and cutting oxygen supply at the cutting torch, the problem arises with a view to the greater volume and/or the higher pressure of the latter fuel gas and heating oxygen supply, that the ignition gas mixture flowing at a lower volume and under a smaller pressure will arrive relatively late at the cutter jet.
This is particularly cumbersome in case of cutting torch machines having a plurality of cutting torches since the igniting spark can be generated only depending on the last available volume of the ignition gas mixture of one torch (German Patent Specification No. 3,827,750). In order to reduce the ignition time and to obtain safe ignition, the prior art control and regulation means for ignition gases is so designed that the ignition gas mixture flows to the cutting torch in a larger volume and/or greater pressure relative to the required volume, or the required pressure, respectively, and is adjusted to the required volume, or the required pressure, by a control or regulating means provided near the cutting torch or within the cutting torch. The control or regulating means can in this case be designed as a precision dispensing valve. It can also be provided as a diaphragm having a dispensing bore. At the entrance before the mixer in the fuel gas duct furthermore, a precision dispensing valve for optimizing the fuel gas volume can be provided, whereby at the entrance before the precision dispensing valve, at least one solenoid valve is arranged. The precision dispensing valve may include adjusting means which may be adjusted by control means in response to a predetermined mixing ratio or a predetermined volume of the ignition gas mixture. The basic disadvantages of the ignition gas mixture supply to the cutting torch in parallel to the fuel gas and heating oxygen as well as cutting oxygen have not, however, been solved.